Operating system for aircraft barrier nets

ABSTRACT

Device for operating an aircraft arresting mechanism in which the barrier supporting standard is raised and lowered with respect to the runway by two servomotors, one being larger than the other, the larger one producing the smallest moment and the smaller servomotor producing the largest moment when the standard rests in the lowered position, the moments being so balanced as to exert a downward torque on moments being so balanced as to exert a downward torque on the standard in the lowered position, control means being provided to convert the moments so as to produce a first stage gradual raising operation and a rapid second stage raising operation.

O United States Patent 1 1111 3,724,333

Fonden et al. 1 Apr. 3, 1973 541 OPERATING SYSTEM FOR AIRCRAFT 2,650,7829 1953 Fehring 91 411 R BARRIER NETS 3,181,430 5/1965 Freedy et al..91/413 3,223,382 12/1965 Mercier et al. ...91/411 R 1 lnventorSI Per'l Fond; K8110" "8"! 3,252,381 5/1966 Gratzmuller ..91/411 R Walander,both of Linkoping, Sweden FOREIGN PATENTS OR APPLICATIONS [73] Assignee:Borgs Fabriks AB, Norrkoping, 1,176,822 1/1970 Great Britain ..91/41l BSweden Primary Examiner-Edgar W. Geoghegan [221 Attorney-Munson &Fiddler [21] Appl. No.: 83,439

[57] ABSTRACT [30] Foreign Application Priority D t Device for operatingan aircraft arresting mechanism in which the barrier supporting standardis raised and Dec. 4, 1969 Sweden ..16740 lowered with respect to therunway by two Servomo tors, one being larger than the other, the largerone [52] US. Cl. ..9l/4ll R,9l/413, 60/5l, producing the Smallest momentand the Smaller 60/97 H vomotorproducing the largest moment when thestan- [51] Int. Cl ..Fl5b II/16 dam rests in the lowered position, themoments being [58] held of searchmgl/fll 411 413; 60/97 H so balanced asto exert a downward torque on moments being so balanced as to exert adownward [56] References and torque on the standard in the loweredposition, con- UNITED STATES PATENTS trol means being provided toconvert the moments so as to produce a first stage gradual ra1s1ngoperation 3,237,406 3/ 1966 Spannhake et al. ..60/51 and a rapid secondstage raising operation, 3,547,007 12/1970 Peters ..91/411 R M 3,610,10310/1971 Adams et al. .3. ..91/41l R 4 Claims, 8 Drawing Figures PmmfnmaI973 3 724 333 SHEET 1 [1F 2 PER BORJE FONDEN, et al INVENTOR MUNSON &FIDDLEP. ATTORNEY S SHEET 2 [IF 2 FIGS.

PER BORJE FONDEN et al lNvsN-rofis BY MUNSON & FIDDLER,

ATTORNEY S OPERATING SYSTEM FOR AIRCRAFT BARRIER NETS BACKGROUND OF THEINVENTION When concerned with systems for large aircraft, for examplelarge civil aircraft, the barrier net-supporting standards are generallyof large dimensions. It is required that the net be raised automaticallyand at the last moment and only if and when it is needed so that theraised net does not normally present an obstacle to aircraft landing andtaking off. These requirements mean that the standards and the net mustbe capable of being raised at speeds which render previously known meansand methods unsuitable. The present invention relates to an improvementfor solving this problem.

The present invention therefore relates to an operating system foraircraft barrier nets for raising and lowering pivoted standards thatsupport the net including servomotors that are operated by means of apressure medium used for said operating system for the pur- 2 pose ofproviding the necessary forces and torque.

SUMMARY OF INVENTION The objects and advantages of the invention will beapparent from the accompanying drawings in which:

FIG. 1 is a diagrammatic view of the barrier net standard in its loweredposition;

FIG. 2 is a diagrammatic view showing the commencement of the raisingoperation;

FIG. 3 is a diagrammatic view showing the barrier standard moved into araised position;

FIG. 4 is a diagrammatic view showing the commencement of the loweringof the standard;

FIG. 5 is a diagrammatic view showing the device when the loweringoperation has been completed;

FIG. 6 is a diagrammatic view of a linkage arrangement for theservomotors used in connection with the invention;

FIG. 7 is a diagrammatic view showing the arrangement of FIG. 6 inraised position;

FIG. 8 is a diagrammatic view wherein the smaller one of the servomotorsaccording to the invention is provided with locking means.

The invention is illustrated in the accompanying drawings in which FIGS.1 to 8 inclusive shown the arrangement in different positions.

At 1 in the drawings is shown a standard in its collapsed or loweredposition. The standard is pivotally supported by a pivot pin 2 and canbe optionally provided with a balancing counterweight 3. The standard 1is actuated by two types of servomotor, a large one being shown at 4 anda smaller one at 5. The larger one 4 is adapted to effect the mainstandard-raising operation. FIG. 1 shows a lowered standard in positionto be rapidly raised whenever required. The pressure side 6 of theservomotor 4 is subjected to pressure by a liquid supplied by anaccumulator 7. A pump 8 maintains the pressure at a suitable level. Thepump 8 is driven by a motor 9, which is controlled by a pressure monitor10 actuated by the pressure in a line 1 1, which passes to anelectricallyoperated switching valve 12. A non-retum valve 13 isincorporated in the line 11. As soon as the pressure in the line 11falls below a set value, the pump 8 is started. Positioned between theaccumulator 7 and the pressure side 6 of the servomotor 4 is a line 14,which is so dimensioned that a rapid supply of pressure medium isobtained, that is short and wide.

In order to secure the necessary rapid operating moments, the system isdesigned to carry out the described performances without the presence ofvalves in the line 14.

The larger servomotor 4 is arranged so that when the standard 1 occupiesits lowered position, the servomotor produces the smallest moment, oreven a negative torque and this is achieved by causing the arm alongwhich the torque moment acts, to pass close to the pivot point 2 of thestandard when the standard is lowered. The torque can be a liftingmovement or a moment tending to retain the standard in a loweredcondition, but which however, provides two different variations in theconnection of the smaller servomotor with the system. The smallerservomotor is adapted to provide its approximate largest moment in thelowered position of the standard and the moment is balanced so that,with respect also to the moment produced by the arm of the net and thestandards, the resulting moment with the standard lowered produces arestraining force. As soon as the standard is raised through just a fewdegrees, from its lowered position however, the standard will beactuated by the lifting moment produced by the larger servomotor.

The system is so balanced that if a change in the connection of thesmaller servomotor in the system takes place, the restraining moment isconverted into a raising moment. After this moment has progressed only afew degrees, the torque is increased, as described above, and liftingcontinues until the standard is fully raised. The power transmission inthe smaller servomotor can also be provided, for example by causing thesmaller servomotor to be fully disengaged from the system when in restcondition, and arranging for said servomotor to be pressure-connected tothe pressure side of the servomotor 4 by a valve movement when wishingto raise the standard. In this case only the moment produced by thelarger servomotor and the arm of the net and the standard results in athe downwardly holding force. The pressure side is presumed for bothmotors to produce a lifting moment when the largest forces are requiredhere, and since the pressure side for a given force best decides thedimensions. For the purpose of solely producing a lifting moment, thesystem will also function with single-acting servomotors, althoughdouble-acting cylinders can also be properly used, so that the samehydraulic system can also be used for the lowering movement of thestandards. In this connection it is essential that a short and wideoutlet line 15 is also passed from the drag side, to permit rapid flowof the hydraulic fluid.

The system can also be balanced in a manner whereby the force exerted bythe large motor and the weights of the system provides a lifting effectin the lowered position of the standard. In such case, the drag side ofthe smaller servomotor is connected to the same hydraulic pressuresource as that on the pressure side of the larger servomotor, wherebythe system is balanced in a manner so that the torque, with the additionof the contribution of the smaller servomotor is now adownwardly-holding force. If the pressure is then disconnected from thepressure side of the smaller servomotor or, alternatively, the drag sideof said servomotor is also connected to the system, the standard willimmediately begin to rise. The desired change-over of the smallerservomotor is effected by the valve 12,

operated either from a known automatic net-rigging apparatus or manuallysuch as from the airfield control tower. By using double-actingservomotors and by suitable adjustment of the system, a loweringmovement can also be obtained, if desired, and initiation of the raisingand lowering sequence is effected by an electrically-operated system viaa tripping battery 16. The hydraulic system also includes conventionalcomponents such as a hydraulic fluid sump 17.

FIG. 2 shows the system when lifting has begun. The valve 12 has beenswitched over so that pressure fluid passes to the drag side of themotors, while the opposite side is connected with the sump 17. Thepressure s ide of the servomotor 4 has accumulator pressure, while theopposite side is connected with the sump. The standard is thereby raisedfrom its resting position by the servomotors and, as shown in FIG. 3,moved to raised position essentially by the servomotor 4.

FIG. 4 illustrates a beginning standard lowering operation. The pressureside of the servomotor 4 and the drag side of the motor 5 are connectedto the sump 17, while pressure fluid is passed to the pressure side fromthe pump 8.

FIG. 5 illustrates the position when lowering of the standard has beencompleted. At 18 is indicated a constriction.

The system is designed so that the standard is lowered gently duringemptying of the accumulator 7.

The system has been described with reference to only one standard,although obviously the same system can be used to operate, at leastpartly, both standards. The system shown in the drawings has also beenchosen to illustrate the variation in which the drag side of the smallerservomotor is connected to the ready position for lifting, and liftingis initiated without exposing the pressure side to hydraulic pressure.

It will be understood that the concept of the invention includesvariations other than those described. For example, the smallerservomotor, which according to the foregoing, acts directly on thestandard, may be adapted in different ways to actuate the standardindirectly. This can be accomplished through a linkage system 19 asshown in FIG. 6 wherein the link system, which can be constructed in anumber of different ways, is designed to provide a positive holdingeffect in the lowered position of the standard through an overridemovement, despite the fact that the larger servomotor in this case ispresumed to produce a relatively large moment even in the loweredposition.

A further variation is that the smaller servomotor is adapted to actuatea mechanical locking means 20, as

shown in FIG. 8, which holds the standard securely in its loweredposition, despite the fact that in the ready position a lifting momentis produced on the standard by the larger servomotor 4.

The drawings illustrate one servomotor at 4 and one at 5, but it will beunderstood that there maybe arranged two or more co-operating motors ateach point without departing from the spirit of the invention.

What is claimed is:

1. A device for operating an aircraft arresting device, comprising:

a. a barrier supporting a standard having a fulcrum axis about which thestandard is rotated from a lowered position into a raised positionrelative to a ay; b. a pair of linearly double-acting hydraulic motorscomprising a cylinder, a piston and a piston rod reciprocably mountedtherein, the rods extending outwardly from one end of the cylinders;

c. one of said hydraulic motors having larger capacity than the otherone;

the piston rod of the motor having larger capacity being pivoted to anarm of said standard at a point spaced from the fulcrum axis of said armwhere said rod has its shortest crank lever when the standard is in itslowered position and has its longest crank lever when the standard is inraised position;

. the piston rod of the other one of said motors being pivoted to saidarm at a point spaced from its fulcrum axis where said piston rod hasits longest crank lever when the standard is in its lowered position andhas its shortest crank lever when the standard is in its raisedposition;

f. means for supplying hydraulic fluid to the opposite ends of saidcylinders to move the pistons and the piston rods to raise and lowersaid standard, and

. control means effective to supply hydraulic fluid to one end of saidcylinders to cause the respective piston rods to'produce a torque onsaid arm during the raising and lowering operation of the standard whileevacuating hydraulic fluid from the other end of the cylinders.

2. Device according to claim 1 in which the pressure fluid supply meansincludes at least one accumulator.

3. Device according to claim 1, in which the pressure fluid supply meansincludes means for supplying pressure fluid to the larger one of theservomotors at an increased rate.

4. Device according to claim 1 having means for selectively disengagingand re-engaging the smaller one of the servomotors to the standard.

1. A device for operating an aircraft arresting device, comprising: a. abarrier supporting a standard having a fulcrum axis about which thestandard is rotated from a lowered position into a raised positionrelative to a runway; b. a pair of linearly double-acting hydraulicmotors comprising a cylinder, a piston and a piston rod reciprocablymounted therein, the rods extending outwardly from one end of thecylinders; c. one of said hydraulic motors having larger capacity thanthe other one; d. the piston rod of the motor having larger capacitybeing pivoted to an arm of said standard at a point spaced from thefulcrum axis of said arm where said rod has its shortest crank leverwhen the standard is in its lowered position and has its longest cranklever when the standard is in raised position; e. the piston rod of theother one of said motors being pivoted to said arm at a poiNt spacedfrom its fulcrum axis where said piston rod has its longest crank leverwhen the standard is in its lowered position and has its shortest cranklever when the standard is in its raised position; f. means forsupplying hydraulic fluid to the opposite ends of said cylinders to movethe pistons and the piston rods to raise and lower said standard, and g.control means effective to supply hydraulic fluid to one end of saidcylinders to cause the respective piston rods to produce a torque onsaid arm during the raising and lowering operation of the standard whileevacuating hydraulic fluid from the other end of the cylinders. 2.Device according to claim 1 in which the pressure fluid supply meansincludes at least one accumulator.
 3. Device according to claim 1, inwhich the pressure fluid supply means includes means for supplyingpressure fluid to the larger one of the servomotors at an increasedrate.
 4. Device according to claim 1 having means for selectivelydisengaging and re-engaging the smaller one of the servomotors to thestandard.